import React, { useEffect, useState } from 'react';
import { auditLogsApi } from '../api/client';
import { format } from 'date-fns';

function DiffView({ changes }) {
  const { before, after } = changes || {};
  if (!before && after) {
    return <span className="text-green-700 text-xs">Created: {JSON.stringify(after, null, 2)}</span>;
  }
  if (before && !after) {
    return <span className="text-red-700 text-xs">Deleted record</span>;
  }
  if (before && after) {
    const keys = Object.keys({ ...before, ...after }).filter(
      (k) => JSON.stringify(before[k]) !== JSON.stringify(after[k])
    );
    if (keys.length === 0) return <span className="text-gray-400 text-xs">No field changes detected</span>;
    return (
      <dl className="text-xs space-y-1">
        {keys.map((k) => (
          <div key={k} className="grid grid-cols-3 gap-2">
            <dt className="font-medium text-gray-600">{k}</dt>
            <dd className="text-red-600 line-through col-span-1 truncate">{String(before[k] ?? '')}</dd>
            <dd className="text-green-700 col-span-1 truncate">{String(after[k] ?? '')}</dd>
          </div>
        ))}
      </dl>
    );
  }
  return null;
}

const ACTION_BADGE = {
  CREATE: 'bg-green-100 text-green-800',
  UPDATE: 'bg-yellow-100 text-yellow-800',
  DELETE: 'bg-red-100 text-red-800',
};

export default function AuditLogSection({ tableName, recordId }) {
  const [logs, setLogs] = useState([]);
  const [total, setTotal] = useState(0);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);
  const [expanded, setExpanded] = useState(null);

  useEffect(() => {
    setLoading(true);
    auditLogsApi
      .list({ tableName, recordId, limit: 50 })
      .then(({ logs, total }) => {
        setLogs(logs);
        setTotal(total);
      })
      .catch((e) => setError(e.message))
      .finally(() => setLoading(false));
  }, [tableName, recordId]);

  return (
    <section aria-label="Modification History" className="mt-8">
      <h3 className="text-base font-semibold text-gray-800 mb-3 flex items-center gap-2">
        <svg className="w-4 h-4 text-gray-500" fill="none" viewBox="0 0 24 24" stroke="currentColor">
          <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2}
            d="M12 8v4l3 3m6-3a9 9 0 11-18 0 9 9 0 0118 0z" />
        </svg>
        Modification History
        {total > 0 && (
          <span className="text-xs font-normal text-gray-500">({total} entries)</span>
        )}
      </h3>

      {loading && <p className="text-sm text-gray-500">Loading history…</p>}
      {error && <p className="text-sm text-red-600">{error}</p>}
      {!loading && !error && logs.length === 0 && (
        <p className="text-sm text-gray-400 italic">No modification history yet.</p>
      )}

      {logs.length > 0 && (
        <div className="border border-gray-200 rounded-lg overflow-hidden divide-y divide-gray-100">
          {logs.map((log) => (
            <div key={log.id} className="bg-white">
              <button
                className="w-full text-left px-4 py-3 flex items-center gap-3 hover:bg-gray-50 transition-colors"
                onClick={() => setExpanded(expanded === log.id ? null : log.id)}
                aria-expanded={expanded === log.id}
              >
                <span className={`shrink-0 px-2 py-0.5 rounded text-xs font-semibold ${ACTION_BADGE[log.action] || 'bg-gray-100 text-gray-700'}`}>
                  {log.action}
                </span>
                <span className="text-xs text-gray-500 shrink-0">
                  {format(new Date(log.timestamp), 'yyyy-MM-dd HH:mm:ss')}
                </span>
                <span className="text-xs text-gray-400 truncate flex-1">
                  {log.table_name} / {log.record_id}
                </span>
                <svg
                  className={`w-4 h-4 text-gray-400 shrink-0 transition-transform ${expanded === log.id ? 'rotate-180' : ''}`}
                  fill="none" viewBox="0 0 24 24" stroke="currentColor"
                >
                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M19 9l-7 7-7-7" />
                </svg>
              </button>
              {expanded === log.id && (
                <div className="px-4 pb-3 bg-gray-50 border-t border-gray-100">
                  <DiffView changes={log.changes} />
                </div>
              )}
            </div>
          ))}
        </div>
      )}
    </section>
  );
}